An American League slugger has won eight of the 10 Home Run Derbys since the three-round, 10-out format was adopted in 1991, but that trend may be reversed this year at SAFECO Field in Seattle as the National League sends a trio of slugging outfielders to the contest in search of back-to-back champions.

Defending Home Run Derby champion Sammy Sosa; Giants outfielder Barry Bonds, who with 39 home runs at the break is ahead of Mark McGwire's record pace en route to 70 in 1998; Arizona outfielder Luis Gonzalez, who is hot on Bonds' tail with 35 homers; and Rockies first baseman Todd Helton, who has hit 26 homers, will represent the NL in the Century 21 Home Run Derby, which is live now on ESPN.

Last year, Sosa ended Ken Griffey Jr.'s two-year reign as Home Run Derby champion at Turner Field in Atlanta. Sosa beat Griffey 9-2 in the finals and hit 26 overall, including a pair of 508-foot shots -- one to the 755 Club in the left-field upper deck and one that came to rest atop the second green batter's backdrop in straightaway center.

"It's something that you enjoy," Sosa said. "I'm a competitive guy. You always want to be prepared to be there. Last year was one of those years when I really, really made people happy and that brings me a lot of happiness. I'm going to go out there today, see what's going on and hopefully God will bless me again."

The American League counters with hometown hero Bret Boone, who with 22 home runs almost has reached his career high (24); former hometown hero Alex Rodriguez; Angels third baseman Troy Glaus, who led the Major Leagues with 47 home runs last season; and A's first baseman Jason Giambi, who will be making his first Home Run Derby appearance.

Boone, enjoying a breakout season in his return to the Mariners, made light of any home-field advantage.

"I win automatically because I know all the quirks," Boone said. "Actually, this thing for me is to try and not embarrass myself."

Alex Rodriguez will now participate in this year's Home Run Derby.

A-Rod, who left Seattle during the offseason for a 10-year, $252 million deal with the Rangers, knows he won't be a fan favorite in the city where he played for five-plus seasons.

"I'm going to do the best I can try not to let the boos bother me," he said.

With Boone feeling the hometown pressure and A-Rod battling a hostile crowd, do Glaus or Giambi stand a better chance of winning it for the AL?

"I think any of us is capable of winning it," Glaus said, "but I think my chances are as good as anyone's. I didn't bring my own pitcher with me, though."

"I doubt that I will win it," said Giambi, who is having another outstanding season (.322, 19 HRs, 60 RBIs). "I'm just going to go out there and have fun and enjoy every minute of it.

"Luis Gonzalez and Barry Bonds have that home run stroke going. It should be fun this year. I have competed in some of these (although he's never been in the All-Star Home Run Derby), and it's a lot different when they pull that (batting cage) away. The game changes all of a sudden."

"I don't hit tape-measure shots. I hit line drives and squeakers that just clear the wall. As long as it goes over the fence, that's all that counts."

One thing in Gonzalez' favor is SAFECO Field, which will provide the left-handed batters -- Bonds, Gonzalez, Helton and Giambi -- with a distinct advantage. It is 327 feet down the right-field line compared to 331 down the left-field line, and 387 feet to the right-center power alley as compared to 390-feet to left center. Also, the deepest part of the park, a 405-foot nook in center field, is left of second base, giving a left-handed batter an advantage down the line, in the alley and to center field.

Bonds ('96) and Sosa are the only former champions participating, while Boone, Gonzalez, Helton, Glaus and Giambi are making their first Home Run Derby appearances. Although the AL has dominated the Home Run Derby titles over the last 10 years, the homer totals have been closer. The AL has hit more home runs in eight Derbys while the NL has led in seven, and the AL holds a 294-263 lead in home runs overall.

While Sosa is back to defend his title, Griffey, a three-time Derby champion ('94, '98, '99) missed most of the first half of the season due to a hamstring injury did not make the NL All-Star team. A player must make the All-Star Game to be eliglible to participate, so McGwire, the single-season home run king, also will not be in this year's contest. Regardless, there promises to be plenty of fireworks as there has been every year but one -- the 1988 contest in Cincinnati was rained out -- since the popular event began in 1985.

From 1985-90, the Home Run Derby was structured as a two-inning event with each player getting five outs per inning. Since 1991, eight players, four from each league, are chosen to participate in a three-round contest to determine the champion. Each player receives 10 outs per round to hit as many home runs as they can. The top four, regardless of league affilitation, advance to the second round. If a tie exists among players for advancement into Round Two, the player with the most regular-season home runs at the All-Star break advances. The second tie-breaker, if necessary, is distance of longest home run in Round One.

Home runs do not carry over from round to round, and in the second round the players are seeded 1-4.The No. 2 seed faces No. 3 and No. 1 faces No. 4, with the winners advancing to the Championship Round. If a tie exists among players for advancement into Championship Round the player with the most home runs in Round One advances. The second tie-breaker is most regular-season homers at the All-Star break and the third is distance of longest home run in either of the first two rounds.

If the two finalists hit the same number of home runs in The Championship Round, the Home Run Derby will go into "Home Run Derby Showdown." Each player gets one swing, and the first player to hit a home run when the other makes an out is the champion.